Inking units or dampening units of printing presses are employed for conveying an ink or a required dampening agent from appropriate supply devices to printing zone. Rollers or cylinders are provided in the inking unit or in the dampening unit for forming the required ink film or dampening agent film. The term roller and cylinder have the same meaning for understanding the present invention and will be used interchangeably. The rollers come into contact with each other along so-called roller strips. The ink film or the dampening agent film can be transferred in the roller strips from one roller to another roller.
Rollers, which are adjustably supported in a machine frame, are provided in such inking units or dampening units. A contact pressure in the roller strips can be changed by displacing these adjustably seated rollers with respect to the other rollers. An inking unit, with a distribution roller seated fixed in the frame and with a forme cylinder also seated fixed in the frame, is known from EP 0 826 501 A1. Inkis transferred from the distribution roller to the forme cylinder by use of an application roller that is arranged between the distribution roller and the forme cylinder. The application roller is itself adjustably seated in the machine frame and can be pressed, with an adjustable force, into the gap between the distribution roller and the forme cylinder. The device for seating the application roller is embodied in this prior device in such a way that the force with which the application roller is pressed into the gap between the distribution roller and the forme cylinder always acts along a bisecting line of an angle. In other words, although the size of the force for pressing the application roller can be changed, the direction of the force is unchangeably preset by the structural embodiment of the setting device. Thus, only the size of the contact pressure force can be changed for setting the contact pressure in the roller strips between the forme cylinder and the distribution roller on the one hand, and the application roller on the other hand. The resulting contact pressures in the roller strips ensue on the basis of the preset geometry.
A device for clamping bearing bushes of printing and forme cylinder bearing of a printing press is known from the Letters Patent DD 64 064. The device provides a hydraulic force for pressing the bearing bushes against the bore wall of the machine frame. The bearing bushes consist of two bushing sleeves shrunk on each other. Two hydraulically chargeable pressure chambers have been worked into the inner wall of the outer bearing bush, which pressure chambers are placed on both sides at 120° in respect to the resultant of the mean forces acting on the bearing. The true running properties of the cylinders are improved with this device, because a movement of the cylinders which is, to a large extent, vibration-free is achieved by the removal of the play which the bearing bushes have in the bore of the machine frame which receives them.
Letters Patent DE 15 61 014 C1 shows a roller bearing which is adjustable in only one direction, and which is used, in particular, for distribution and application rollers of inking units of printing presses. Setting assemblies, for adjusting the roller transversely in respect to its axis, are provided. The setting assemblies are arranged between a bearing journal connected with the frame wall and a housing, which housing receives one roller end and which is preferably embodied in a cup shape. The bearing journal and the housing are connected with each other by spring elements, which act oppositely to the setting assemblies; Here, the spring elements are preferably embodied as radially extending rubber bumpers, and the setting assemblies acting on the bearing journal are either embodied as a radially arranged setting screw, or as two setting screws arranged at 45°. In accordance with a further embodiment, the engagement or the disengagement of the roller, and therefore the adjustment of the roller bearing, can also take place by the use of two pressure chambers, which are diametrically arranged inside the housing and which can be acted on by air or a fluid, wherein the pressure chambers acting against each other are selectively charged with pressure.
In the embodiments disclosed in DE 15 61 014 C1, the placement of the adjustably seated roller against adjoining rollers preferably takes place wherein a pressure chamber inserted into an elastic body, or a movably arrange piston, are put under pressure. Because of the tendency of the volume of the pressure chamber to expand under pressure, the pressure chamber or the piston, which is moved by pressure, causes the adjustably seated roller to move along an actuation path. The contact pressure in the roller strip between the adjustably seating roller and its adjoining rollers is accomplished by the setting of setting screws. The disengagement of the adjustably seated roller takes place by releasing the pressure in the pressure chamber and preferably by a restoration of the resiliently deformed elastic body. Accordingly, the engagement or disengagement of the rollers is provided by the selective supply and removal of a pressure medium, while the setting of the rollers, in relation to each other, is provided by the actuation of one or of several radial setting screws. Different mechanisms are required for the engagement and disengagement of the rollers and for the setting of the rollers in respect to each other.
A device for engaging and disengaging application rollers in an inking unit of rotary printing presses, by use of pistons charged with a pressure medium, is known from GB 1 213 935 A. Each application roller is seated on a pivot lever which is pivotable around an inking unit roller. The bearing of the application roller is connected with a piston, which is arranged in the pivot level, which is movable in the longitudinal direction of the latter and which can be charged with a pressure medium. During the charging of this piston with a pressure medium, the application roller is placed against, or is moved away from the ink unit roller. The pivot lever is pivotable by use of a further piston which is charged with a pressure medium arranged in a cylinder. In the course of being charged with a pressure medium, this further piston pivots the pivot lever around the inking unit roller, and, in the process, places the application roller against a forme cylinder, or moves it away from the forme cylinder. In connection with this device, it is disadvantageous that the pistons and pivot levers require a considerable amount of structural space for their arrangement and for performing the movement in the course of their actuation in the printing group. They are also exposed to considerable soiling, for example by sprayed ink fog, because of their immediate closeness to ink-carrying rollers, from which exposure a certain susceptibility to malfunctions arises. Time-intensive and cost-intensive cleaning and maintenance work are required in a hard to access place of the printing press.
A device for setting a contact pressure between rollers of a printing press is known from DE 100 01 582 A1. Hydraulic actuating elements, which are preferably embodied as double piston cylinders, are arranged between the adjoining rollers.